The invention concerns a ceiling or overhead air conditioner unit that is configured to fit into an available ceiling space, e.g., a two-foot by four-foot dropped ceiling space. The invention is more particularly concerned with a self-contained ceiling mounted unit that has its interior configured so that the inside (evaporator) air and the exhaust heat (condenser) air are moved in separate paths in the unit. The indoor discharge air, conditioned for temperature and humidity, is directed downward through a filter of suitable grade for the application. In some cases, this can be a high-efficiency particulate air (HEPA) filter, and in other applications the filter can be a so-called "absolute" filter, or a chemical-absorptive filter, such as a carbon or carbon-impregnated filter.
Conventional ceiling mounted air conditioner units typically incorporate only the evaporator side of the refrigeration circuit, and employ a separate outdoor condenser unit. This arrangement is referred to as a split system. Conventional ceiling mounted HEPA air filtration units typically involve air handling only, and do not heat or cool the air, nor do they control humidity. While it is sometimes advantageous to create an underpressure in a given space (so that contaminants do not leak out from the space) or to create an overpressure (so that contaminants are forced out, and do not migrate into the space), ceiling mounted self-contained air handling or air conditioning units have not had the capability for either.
There are also several ceiling-mounted filter and blower assemblies available, which are dimensioned to fit into a 2' by 4' ceiling space for providing clean air to a workplace.
Leader et al. U.S. Pat. No. 5,470,363 describes a compact filter and blower assembly with an air intake at the top center of the housing or cabinet, where the intake air encounters a centrifugal blower. A baffle system directs the air downward through a HEPA filter into the room space. The air is not cooled, dehumidified, or otherwise conditioned than by filtering it. Davis U.S. Pat. No. 4,560,395 describes another compact centrifugal fan and blower assembly. Garay et al. Pat. No. 5,053,065 describes a low-profile blower arrangement with a pair of air inlets and twin backward-curved centrifugal impellers. None of these systems employs an air conditioner, either integrated with the blower and filter unit, or piggy-backed onto the unit in the ceiling space.
Candeloro U.S. Pat. No. 5,107,687 is typical of a modular air conditioning system that fits above a suspended ceiling and directs air through channeling in the space above the suspended ceiling. Nelson U.S. Pat. No. 5,152,814 relates to a blower unit for use in isolating patents having contagious respiratory disease. The blower draws air from the patient's room and filters the discharged air to maintain the room at a negative pressure. Again, none of these deals with the problem of providing all the required equipment for conditioning and filtering room air in the geometry of a standard 2' by 4' ceiling space.
The equipment now available or known is not well adapted for ganging units together, either side by side or end to end, and does not provide for field selecting condenser-side intake and outlet at either the end, the side, or the top, as may be required for a given installation.